고밀도 STS316L 합금 적층 성형체의 제조공정 최적화 및 인장 특성 연구

송영환 한국결정성장학회 2023 한국결정성장학회지 Vol.33 No.6

STS316L 합금의 Laser powder bed fusion 공정 최적화를 위하여 Laser power, Scan speed 및 Hatching distance의 공정조건을 제어하면서 투입 레이저 에너지 밀도와 조형체의 상대밀도와의 상관관계를 연구했고, 최적조건으로 제작된 조형체의 적층 방향에 따른 인장특성 변화를 분석했다. STS316L 분말을 에너지밀도가 55.6J/mm3, 83.3 J/mm³ 및 111.1 J/mm³ 인 조건에서 적층 성형한 결과, 투입 레이저 에너지밀도가 83.3 J/mm³이며 , Power 및 Scan speed 각각 225 W, 1000 mm/s 인 조건에서 가장 안정적으로 고밀도 STS316L 샘플을 제작할 수 있었다 . 최적공정조건을 이용해 적층 방향과 인장방향이 각각 0°, 45°, 90°인 인장시험편을 제작하여 인장특성을 비교한 결과 적층 방향과 인장방향이 수직인 시험편의 항복강도, 인장강도 및 연신율이 가장 우수한 것이 확인되었다. 적층 방향과 수직 방향으로의 이방성을 가지는 기공 및 Lack of fusion 결함이 응력집중을 야기하여 인장특성을 열화 시키기 때문인 것으로 추정된다. To optimize the process parameters of laser powder bed fusion process to fabricate the high density STS316L alloy, the effect of laser power, scanning speed and hatching distance on the relative density was studied. Tensile properties of additively manufactured STS316L alloy using optimized parameters was also evaluated according to the build direction. As a result of additive manufacturing process under the energy density of 55.6 J/mm3, 83.3 J/mm³ and 111.1J/mm³, highdensity STS316L specimens was suitably fabricated when the energy density, power and scan speed were 83.3 J/mm³,225 W and 1000 mm/s, respectively. The yield strength, ultimate tensile strength, and elongation of STS316L specimens in direction perpendicular to the build direction, show the most competitive values. Anisotropic shape of the pores and thelack of fusion defects probably caused strain localization which result in deterioration of tensile properties.

STS316L 용접부의 피로거동 및 초음파시럼에 의한 열화특성 평가

남기우,박소순,안석환,도재윤,박인덕 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.2

STS316L은 인성, 연성, 부식저항성 등 우수한 기계적 성질 때문에 에너지환경설비 등 구조물에 널리 이용되고 있다. 그러나, 용접구조물은 가혹한 환경하에서 경년열화가 심각하다. 지금까지의 연구들은 주로 용접부의 피로균열진전거동에 관하여 수행되었고, 피로균열진전속도식의 재료상수와 비파괴적 평가의 상관성에 관한 연구는 거의 없었다. 본 연구는 STS316L 용접부의 피로균열진전 거동을 조사하고, 초음파 파라미터로 열화특성을 평가하고 시간-주파수 분석으로 해석을 하였다. 본 연구 결과는 용접구조물의 사용기간 중 피로수명 등을 예측하기 위한 기초 데이터로서 사용될 수 있다. STS316L had been used as the structural material for energy environmental facilities, because austenite stainless steels like 316L have superior mechanical properties of which toughness, ductility, corrosion resistant and etc. However, those welded structures are receiving severe damage due to increasing of the aged degradation. Most studies until now have been carried out against fatigue bahaviors of weldments, and were not well studied on nondestructive evaluation methods. In this study, the fatigue crack propagation behavior of STS316L weldment usually used for vessels of the nuclear power plant was investigated. Also, the degradation characterstics of 316L stainless steel weldments were evaluated by the ultrasonic parameter such as ultrasonic velocity, attenuation factor and time-frequency analysis. The results of this study can be used as a basic data for the prediction of the fatigue crack life of weldments structures without disjointing or stopping service of structures in service.

R.F. sputtering 방법에 의해 c-BN 표면처리된 316L 오스테나이트계 스테인리스 강의 내마모특성 향상

이광민,정세훈,박성태,Lee, Kwang-Min,Jeong, Se-Hoon,Park, Sung-Tae 한국재료학회 2010 한국재료학회지 Vol.20 No.4

Cubic boron nitride (c-BN) is a promising material for use in many potential applications because of its outstanding physical properties such as high thermal stability, high abrasive wear resistance, and super hardness. Even though 316L austenitic stainless steel (STS) has poor wear resistance causing it to be toxic in the body due to wear and material chips, 316L STS has been used for implant biomaterials in orthopedics due to its good corrosion resistance and mechanical properties. Therefore, in the present study, c-BN films with a $B_4C$ layer were applied to a 316L STS specimen in order to improve its wear resistance. The deposition of the c-BN films was performed using an r.f. (13.56 MHz) magnetron sputtering system with a $B_4C$ target. The coating layers were characterized using XPS and SEM, and the mechanical properties were investigated using a nanoindenter. The friction coefficient of the c-BN coated 316L STS steel was obtained using a pin-on-disk according to the ASTM G163-99. The thickness of the obtained c-BN and $B_4C$ were about 220 nm and 630 nm, respectively. The high resolution XPS spectra analysis of B1s and N1s revealed that the c-BN film was mainly composed of $sp^3$ BN bonds. The hardness and elastic modulus of the c-BN measured by the nanoindenter were 46.8 GPa and 345.7 GPa, respectively. The friction coefficient of the c-BN coated 316L STS was decreased from 3.5 to 1.6. The wear property of the c-BN coated 316L STS was enhanced by a factor of two.

오스테나이트계 스테인리스강과 니켈합금의 해수 농도 변화에 따른 전기화학적 부식 손상 특성

허호성 ( Ho-seong Heo ),김성종 ( Seong-jong Kim ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.5

Due to advancement of the industry, operation of a device in a harsh environment is increasing. Especially, the marine environment contains Cl^- ions which causes localized corrosion such as pitting and crevice corrosion of stainless steel and various metals. In this study, electrochemical corrosion behaviors of austenitic stainless steel (STS 316L) and nickel alloy (Inconel 600) with different seawater concentrations (fresh water, seawater, mixed water) were investigated. The STS 316L and Inconel 600 were etched in 10% oxalic acid and composed of an austenitic phase. Results of Tafel analysis in seawater showed that STS 316L and Inconel 600 presented the highest corrosion current densities of 7.75 × 10^-4 mA/㎠ and 1.11 × 10^-4 mA/㎠ and the most negative pitting potentials of 0.94 V and 1.06 V, respectively. The maximum damage depths and surface damage ratio by pitting corrosion increased with chloride concentration. The STS 316L had higher PREN than Inconel 600. However, the surface damage and weight loss of Inconel 600 were superior to STS 316L. It was difficult to compare the pitting resistance of STS 316L based on Fe and Inconel 600 based on Ni with PREN simply.

GTAW 용접에 의한 STS 304 및 STS 316L의 이종용접 시 기계적 특성 평가

박재철(Jae-Cheul Park),한민수(Min-Su Han),장석기(Seok-Ki Jang),김성종(Seong-Jong Kim) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.10

This papers compared the mechanical characteristics and the weldability of GTAW by identical as well as dissimilar welding for STS 304 and STS 316L. It applied to double wall gas pipe of duel fuel engine for LNG carrier. The result of welded zone microstructure observation, a degree of acicular ferrite in STS 304 welded zone presented more than STS 316L. Beside, the variety ferrite phases were presented over the most of welded zone. As a result, it is concluded that the hardness of STS 304 welded zone presented higher than STS 316L welded zone by these effects.

액화수소 저장 탱크용 STS 304, STS 316L 소재의 레이저 용접 적용을 위한 기초 BOP 연구

하을용,표창민,김재웅 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.6

Liquified hydrogen is considered a new energy resource to replace conventional fossil fuels due to environmental regulations by the IMO. When building tank for the storage and transportation of liquified hydrogen, materials need to withstand temperatures of -253°C, which is even lower than that of LNG (-163°C). Austenitic stainless steel mainly used to build liquified hydrogen tank. When building the tanks, both the base material and welding zone need to have excellent strength in cryogenic condition, however, manual arc welding has several issues due to prolonged exposure of the base material to high temperatures. Laser welding, which has some benefits like short period of exposure time and decrease of thermal affected zone, is used many industries. In this study, laser bead on plate welding was conducted to determine the laser butt welding conditions for STS 304 and STS 316L steels. After the BOP test, cross-section observations were conducted to measure and compare four bead parameters. These tendency result of laser BOP test can be used as conditions laser butt welding of STS 304 and STS 316L steel.

A Study on the Galvanic Corrosion for Zirconium with Titanium and 316L Stainless Steel

백신영 해양환경안전학회 2013 해양환경안전학회지 Vol.19 No.3

The coastal area of Republic of Korea is very clean compared to other countries. In this reason, west coastal area of our country is a good place for breeding up a fish such as shrimp. In winter season, the heating system is required for preventing shrimp death caused by freezing in the farm. The heater in the heating system for fishery's farm is operated very severe combating corrosion due to high accumulation by feeding material and high temperature in heated sea water. Almost all manufactured heaters of STS 316L and Ti material are scrapped every year due to heavy corrosion such a general and crevice corrosion. For comparing the general and galvanic corrosion in new heater material, the test material of Zirconium (Zr), Titanium (Ti) and STS 316L are tested by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), current density-time methods and microscopic examination in a 3.5% NaCl solution. The corrosion potential (Ecor) measured by potentiodynamic polarization for Zr, Ti and STS 316L reveals -198, -250 and -450mV, corrosion current density 0.5, 2.5 and 6.5㎂/cm^2 respectively. The film resistance measured by EIS are Zr 63,000, Ti 39,700 and 316L 3,150Ω, and the current of Zr-Ti couple is 0.03㎂, whereas Zr-316L SS is 0.1㎂. According to the result of this experiment in 3.5% NaCl solution, Zr is excellent corrosion resistance material than Ti and STS 316L.

A Study on the Galvanic Corrosion for Zirconium with Titanium and 316L Stainless Steel

Shin-Young Baik 해양환경안전학회 2013 海洋環境安全學會誌 Vol.19 No.3

The coastal area of Republic of Korea is very clean compared to other countries. In this reason, west coastal area of our country is a good place for breeding up a fish such as shrimp. In winter season, the heating system is required for preventing shrimp death caused by freezing in the farm. The heater in the heating system for fishery's farm is operated very severe combating corrosion due to high accumulation by feeding material and high temperature in heated sea water. Almost all manufactured heaters of STS 316L and Ti material are scrapped every year due to heavy corrosion such a general and crevice corrosion. For comparing the general and galvanic corrosion in new heater material, the test material of Zirconium (Zr), Titanium (Ti) and STS 316L are tested by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), current density-time methods and microscopic examination in a 3.5% NaCl solution. The corrosion potential (Ecor) measured by potentiodynamic polarization for Zr, Ti and STS 316L reveals -198, -250 and -450mV, corrosion current density 0.5, 2.5 and 6.5μA/cm2 respectively. The film resistance measured by EIS are Zr 63,000, Ti 39,700 and 316L 3,150Ω, and the current of Zr-Ti couple is 0.03μA, whereas Zr-316L SS is 0.1μA. According to the result of this experiment in 3.5% NaCl solution, Zr is excellent corrosion resistance material than Ti and STS 316L.

A Study on the Galvanic Corrosion for Zirconium with Titanium and 316L Stainless Steel

Baik, Shin-Young The Korean Society of Marine Environment and safet 2013 해양환경안전학회지 Vol.19 No.3

The coastal area of Republic of Korea is very clean compared to other countries. In this reason, west coastal area of our country is a good place for breeding up a fish such as shrimp. In winter season, the heating system is required for preventing shrimp death caused by freezing in the farm. The heater in the heating system for fishery's farm is operated very severe combating corrosion due to high accumulation by feeding material and high temperature in heated sea water. Almost all manufactured heaters of STS 316L and Ti material are scrapped every year due to heavy corrosion such a general and crevice corrosion. For comparing the general and galvanic corrosion in new heater material, the test material of Zirconium (Zr), Titanium (Ti) and STS 316L are tested by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), current density-time methods and microscopic examination in a 3.5% NaCl solution. The corrosion potential (Ecor) measured by potentiodynamic polarization for Zr, Ti and STS 316L reveals -198, -250 and -450mV, corrosion current density 0.5, 2.5 and $6.5{\mu}A/cm^2$ respectively. The film resistance measured by EIS are Zr 63,000, Ti 39,700 and 316L $3,150{\Omega}$, and the current of Zr-Ti couple is $0.03{\mu}A$, whereas Zr-316L SS is $0.1{\mu}A$. According to the result of this experiment in 3.5% NaCl solution, Zr is excellent corrosion resistance material than Ti and STS 316L.

수퍼 2상 스테인리스강의 부식 저항성에 관한 연구

강흥주(HEOUNG-JOO KANG),남기우(KI-WOO NAM),안석환(SEOK-HWAN AHN),강창룡(CHANG-YONG KANG),도재윤(JAE-YOON DO),박인덕(IN-DUCK PARK) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.2

The corrosion resistance of super duplex stainless steel on both its fibrous and dispersed phases was investigated. These structures consist of various volume fraction and distribution of austenite structure, which were obtained by changing the heat treatment temperature and cycle. The fibrous phase had higher austenite volume fraction than that of the dispersed phase at the same temperature. Corrosion resistance of super duplex stainless steel was evaluated through an immersion test and an impingement test, using 35% HCl and sea water, respectively. Super duplex stainless steel was compared with STS316L and STS304. The corrosion resistance of super duplex stainless steel was superior to STS316L and STS304. The dispersed phase of super duplex stainless steel was more stabilized than the fibrous phase in corrosion. The magnitude of corrosion rate was in order STS304, STS316L, fibrous phase of super duplex stainless steel and dispersed phase of super duplex stainless steel.